Figure 5.

Effects of dopamine and verapamil on frequency and amplitude of cytosolic calcium and muscle contraction are quantified in zebrafish heart. The frequency of the heart oscillation was measured by analyzing the peak-to-peak interval of the oscillations in embedded (A,B) and anesthetized (C,D) fish. The frequencies of muscle contraction (A,C) and cytosolic calcium (B,D) were averaged in fish treated with the vehicle (ctrl), dopamine (DA), or verapamil (VA). Verapamil significantly decreases the frequency of oscillations of both cytosolic calcium and muscle contraction in anesthetized fish. The magnitude of the heart oscillation was measured by analyzing the peak-to-valley amplitude of the oscillations in embedded (E,F) and anesthetized (G,H) fish. The magnitudes of muscle contraction (E,G) and cytosolic calcium (F,H) were averaged accordingly. Both dopamine and verapamil significantly increase the magnitude of heart muscle contraction in the anesthetized zebrafish heart. While dopamine increases the amplitude of calcium, verapamil decreases the calcium amplitude in anesthetized fish. Asterisks denote a significant difference compared to control. N = 6.